Round-to-rectangular heat exchanger



J y 20, 1955 A. J. CHAPlN 3,195,623

ROUND-TO RECTANGULAR HEAT EKCHANGER Drig i pal Filed Nov. '1, 1958 a Sheets-Sheet 1 INVHVTOR. ALMON J. CHAPI N ATTORNEYS July 20, 1965 J. CHAPIN 3,195,623

ROUND TOREGTANGULAR HEAT EXCHANGER 2 Sheets-Sheet 2 Original Filed Nov. 7, 1958 INVENTOR. FGu642f ALMON J. CHAPIN ATTORNEYS United States Patent 0 5 Claims. c1. res-r29 his ap hcation is a divisional application of my copending application Serial No. 772,508 filed November 7, 1958, and now abandoned.

This invention relates to improvements in heat exchang ers and more particularly to a round-to-rectangular heat exchanger.

One of the objects of the present invention is to provide a round-to-rectangular heat exchanger as a one piece article.

A further object of the present invention is to provide a heat exchanger characterized by its inexpensive manufacturing cost, structural simplicity, strong and sturdy nature, ease of manufacture and use, and/ or multiplicity of functional advantages.

Other features of this invention reside in arrangement and design of parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set forth in the appended claims.

The words rectangle and rectangular are intended herein to cover generically both a rectangle with equal length sides called a square and a conventional rectangle with adjacent sides of unequal lengths. Although a square form is specifically described hereinafter, the description applies equally well to a rectangular form.

PEG. 1 is a perspective view of a typical round-to-square heat exchanger assembled with the associated parts of a furnace but with the furnace casing removed and shown in dot-dash lines for clarity of illustration of the internal components of the furnace, and with a portion of the furnace cut away to show a portion of the interior thereof;

PEG. 2 is a horizontal sectional view taken along the lhie 22 of FIG. 1;

FIG. 3 is a perspective view of a form of round-tosquare heat exchanger illustrated in FIG. 1;

PEG. 4 is a perspective view of a second form of roundto-square heat exchanger adapted to be readily substituted for the FIG. 3 form in PEG. 3;

FIG. 5 is a perspective view of a third form of heat exchanger; while FIG. 6 is a perscective view of a fourth form of heat exchanger.

Before each heat exchanger and method of forming here disclosed is specifically described, it is to be understood that the invention here involved is not limited to the structural details, arrangement of parts, or method stops here disclosed since the present invention may take various forms. It also is to be understood that the phraseology or terminology herein employed is for purposes of description and not of limitation since the scope of the present invention is denoted by the appended claims.

The furnace in PEG. 1 includes an outer casing 19,

"ice

shown in dot-dash lines, square in horizontal cross section to fit neatly and compactly into a corner of a basement or into a furnace room in a house. Casing llti has a cold air inlet near its lower end. Within casing lid is located a round-to-square heat exchanger 12 of sleeve construction with a vertical central axis with this heat exchanger including a fire pot 12a, circular in horizontal cross section; a burner pouch hole 121; surrounded by a collar ll. secured to fire pot 12a; and a combustion chamber 126, square in horizontal cross section, having a fume outlet hole 12d. Cover 13 is welded to top end 19-h to close the top of chamber A gas or oil burner i l, or suitable coal grates, are provided within the fire pot 12a in the conventional manner with access thereto through the burner pouch hole 121'). A fine 15, of tubular hollow square construction, is su ported by spaced straps 16 secured to the exterior surface or" heat exchanger 12. Flue 15 has an inner wall and an outer wall 3% providing a passage therebetween through which the hot fine gases can travel from combustion chamber 32c through pipe 17, secured at onposite ends to heat exchanger 12 and inner wall lie, and an outlet smoke pipe is, secured at its inner end to the outer wall 155 and extending through casing 19 to a chimney. The hollow square, provided between combustion chamber 12c and flue 325, provides a path 1? for heating the cold air entering inlet lliia and directing this air upwardly to hot air pipes for supplying the house.

The travel of the hot gases and heated air should be readily apparent. The hot gas path is shown by arrows A with the gases traveling upwardly from fire pot 12a through combustion chamber 12c, outwardly through tome outlet hole 12d and pipe 17, around combustion chamber 32c and air outlet path 19 through flue l5, and outwardly through smoke pipe 18 to a suitable chimney. The air from the house rooms to be heated enters as cold air through imet lilo, travels upwardly through casing 10 for heating through parallel paths between line 15 and casing 16} and along path 19 between combustion chamber 320 and line 15 to be collected from these two paths by the upper end of the casing iii and directed through the conventional hot air pipes (not shown) to the rooms to be heated.

The shape of the round-tosquare heat exchanger 12 has advantages. Casing ill and combustion chamber 120, being square in horizontal cross section at upper end 3211, minimize the transverse dimension of the furnace, permit the furnace to be neatly and compactly fitted into a corner of a basement to leave maximum usable basement space, and provide preferred heat transfer surface orientation. Fire pot 312a, being round in horizontal cross section at its lower end 12- will not buckle and/or boom when it changes temperature, as would occur if it were square in horizontal cross section. Hence, the advantage of the round-to-square construction is readily apparent.

FIGS. 3, 4, 5 and 6 show four diiferent forms of roundto-square heat exchangers 1'21, 22, 32 and 42 interchangeably usable in the furnace in the FIG. 1 construction so as to obtain all of the advantages mentioned heretofore for the FIG. 1 construction. These four forms of heat exchangers have generic features. These respective heat exchangers are one piece sleeves having cylindrical lower ends 12;, 221', 32; and 421, square upper ends 12h, 22h, 32k and 42h coaxial with the lower ends, and transition zones 12p, 22p, 32p and 42p located axially between, joining,

' triangle bases 22: 32:1 and 42g being located in and smoothly blending together the cylindrical and square forms from the aforesaid ends.

Each of these heat exchanger forms may be made by my improved low cost method. A flat sheet of metal, such as sheet iron, of square or rectangular outline is bent into a sleeve circular in cross section and generally identical to ends 12f, 22f, 32f and 42 until the opposite ends of the sleeve abut as an element of this sleeve. Then, these abutting ends are welded as a seam 12w, 22w, 32w or 42w to form the longitudinally extending element of the cylinder, which at this point in manufacture is circular in cross section and generally uniform in cross section throughout its length. Then, the sleeve is placed between suitable press dies to deform the other end of the sleeve into a square cross section, as shown by ends 12h, 22h, 32h and 42h, coaxial with the aforementioned cylindrical lower ends.

During this press forming, the dies also deform the transition zones 12p, 22p, 32p and 42p between the sleeve ends to smoothly blend together the cylindrical and square sleeve ends.

It should be readily apparent that in each of the forms, the peripheral dimension of the square end is substantially exactly the same as the round end (the periphery of square end 1211 is substantially the same as circular or round end 127 in FIG. 3), because the sleeve in each form is of substantially uniform cross section before the forming operation.

Each of the four heat exchangers also has other generic structure. These heat exchangers include cover walls 13, 23, 33 and 43 welded or otherwise secured to the top ends of the sleeves to close the upper ends, burner pouch holes 12b, 22b, 32b, and 42b in the walls of the sleeves near their lower ends surrounded by collar 11, 21, 31 and 41 welded thereto; and fume outlet holes 12d, 22d, 32d and 42d through the sleeve walls at the upper ends of the sleeves. In each form, the burner pouch hole and the fume outlet hole are longitudinally aligned. In each form, the outlet hole, such as hole 12d, is equidistant from the corners of the square formed by the upper end, such as end 12h, located along one square edge, and the seam, such as seam 12w, is equidistant from the corners of the square on an adjacent square edge on this upper end, such as end 12b.

The heat exchanger forms in FIGS. 3, 5 and 6 have similar upper sleeve portions. Each has the square section of the upper end extending for a substantial axial extent of the sleeve and forming four 90 degree related rectangular faces 12 32j or 4 2j by the walls of the sleeves with the outlet hole 12d, 32d or 42d extending through one of these faces.

FIGS. 3 and 6 have similarly constructed lower sleeve portions. On each of these forms, the cylindrical section of the lower end extends for a substantial axial extent of the sleeve and forms a circular cylindrical peripheral wall 12g or 42g with at least a major portion of the burner hole 121) or 42b extending through this peripheral wall.

Although only one outlet hole 12a, 22d, 32d or 42d is shown in each sleeve, more outlet holes may be provided,

if desired, in each sleeve.

Heat exchanger 12 in FIG. 3 has a structure substantially different from the others. Here, transition zone 12p comprises wall portions 12r joining the square forming faces 12 and the peripheral wall 12g. The axial length of transition zone 12p is less than the axial length of peripheral wall 12g or of any face 12j.

In FIGS. 4, 5 and 6, the transition zones 22p, 42p are more gradual than the sharp transition zone 12p in FIG. 3. In FIGS. 4, 5 and 6, each transition zone includes four triangles 22f, 321 or 421 in each form; and parts 22x, 32x or 42x of four different oblique cones alternately arranged about the axis of the sleeve. The each 32p and Kt form in a transverse plane and forming a square. The oblique cones in each form have a common circular base 22y, 32y or 42y in a transverse plane and have cone vertices 22z, 32z or 422 located at the junctions of the triangle bases 22q, 32q or 42g.

The second heat exchanger form 22 in FIG. 4 differs from the other by having the transition zone 22p extending throughout the length of'the sleeve 22.

In FIGS. 4 and 5, heat exchangers 22 and 32 have the common circular bases 22y and 32y coplanar with the cylindrical lower ends 22 and 32 In FIG. 6, heat exchanger 42 has the transverse plane, formed by the square comprising the triangular bases 42:1, located below theupper end 42h a first axial distance at least one-fifth of the axial length of the sleeve 42, and has the common circular base 42y located above lower end 42f a second axial distance at least one-fifth of the axial length of the sleeve with transition zone 42p extending the axial distance between this plane and common circular base and having a greater axial length than either of said axial distances.

Many modifications of the illustrated structure come within the scope of this invention. First, burner pouch hole 12b and fume outlet hole 12d are longitudinally aligned (shown as coinciding in FIG. 2) and the axis of each hole extends parallel to a radius of cylindrical lower end 12 (shown as radial in FIG. 2). It should be readily apparent that: (1) holes 12b and may be circumferentially spaced about the longitudinal axis of the sleeve so that each is on a different side of the sleeve instead of being longitudinally aligned, (2) the axis of one or both holes 12!; and 12d may have an alignment with the cylindrical sleeve end 12 other than radial, such as tangential, and (3) one or both holes 12b and 12d may be placed in any desired side, face or portion of the sleeve and need not be in the locations illustrated. Second, the axes of opposite ends, cylindrical end 12 and rectangular end 12b, are coaxial in FIG. 3 with these central longitudinal axes of these ends extending in generally the same direction; these axes are vertical when the heat exchanger 12 is mounted in the operative position in FIG. 1; and the transition zone tip is symmetrically located about the central axis, as shown in FIG. 2, because these axes of opposite ends 1212 and 12 are coaxial.

Various changes in' details and arrangements of parts can be made by one skilled in the art without departing from either the spirit of this invention or the scope of the appended claims.

What is claimed is:

1. In a furnace adapted to burn a combustible fuel, a casing rectangular in horizontal section at least at its end where products of combustion are discharged, a

round-to-rectangular hollow tubular heat exchanger within said casing and completely surrounded by said casing, said heat exchanger and casing being coextensive in length, said heat exchanger being substantially circular in section at a fire pot end thereof, there being an opening in said fire pot end for the introduction of combustion equipment, there being an opening in the opposite end of said heat exchanger for discharge of products of combustion, said heat exchanger being closed save for said openings, the interior of said heat exchanger providing a confining passageway for the products of combustion between said opening and said fire pot end to said discharge opening at said opposite end, said heat exchanger being substantially rectangular in section at said opposite end and spaced inwardly from the rectangular portion of said casing, a smooth round-to-rectangular transition zone in said heat exchanger between said two ends, there being means for air toenter between said casing and heat exchanger at said fire pot end and to leave at said opposite end, said heat exchanger and casting providing a confining passageway in the space between them for said air when flowing between said entering means and said leaving means, whereby said fire pot end has a minimum tendency to buckle and boom under a temperature change, air flows through said transition zone with a minimum of turbulence, and said rectangular casing fits in a square corner of a room.

2. The combination of claim 1 wherein said heat exchanger circular section and rectangular section measure the same about their peripheries.

3. The combination of claim 1 wherein said transition zone is not substantially longer than that required for a short transition from round to rectangular section.

4. The combination of claim 1 wherein said transition zone extends along a major portion of said heat exchanger.

6 5. The combination of claim 1 wherein said transition zone extends along the entire length of said heat exchanger.

References Cited by the Examiner UNITED STATES PATENTS 661,654 11/00 Bates 126-102 2,800,943 7/57 Fuchs et a1. 153-3 OTHER REFERENCES The Welding Encyclopedia, 12th edition, 1947.

CHARLES SUKALO, Primary Examiner. 

1. IN A FURNACE ADAPTED TO BURN A COMBUSTIBLE FUEL, A CASING RECTANGULAR IN HORIZONTAL SECTION AT LEAST AT ITS END WHERE PRODUCTS OF COMBUSTION ARE DISCHARGED, A ROUND-TO-RECTANGULAR HOLLOW TUBULAR HEAT EXCHANGER WITHIN SAID CASING AND COMPLETELY SURROUNDED BY SAID CASING, SAID HEAT EXCHANGER AND CASING BEING COEXTENSIVE IN LENGTH, SAID HEAT EXCHANGER BEING SUBSTANTIALLY CIRCULAR IN SECTION AT A FIRE POT THEREOF, THERE BEING AN OPENING IN SAID FIRE POT END FOR THE INTRODUCTION OF COMBUSTION EQUIPMENT, THERE BEING AN OPENING IN THE OPPOSITE END OF SAID HEAT EXCHANGER FOR DISCHARGE OF PRODUCTS OF COMBUSTION, SAID HEAT EXCHANGER BEING CLOSED SAVE FOR SAID OPENINGS, THE INTERIOR OF SAID HEAT EXCHANGER PROVIDING A CONFINING PASSAGEWEAY FOR THE PRODUCTS OF COMBUSTION BETWEEN SAID OPENING AND SAID FIRE POT END TO SAID DISCHARGE OPENING AT SAID OPPOSITE END, SAID HEAT EXCHANGER BEING SUBSTANTIALLY RECTANGULAR IN SECTION AT SAID OPPOSITE END AND SPACED INWARDLY FROM THE RECTANGULAR PORTION OF SAID CASING, A SMOOTH ROUND-TO-RECTANGULAR TRANSITION ZONE IN SAID HEAT EXCHANGER BETWEEN SAID TWO ENDS, THERE BEING MEANS FOR AIR TO ENTER BETWEEN SAID CASING AND HEAT EXCHANGER AT SAID FIRE POT END AND TO LEAVE AT SAID OPPOSITE END, SAID HEAT EXCHANGER AND CASTING PROVIDING A CONFINING PASSAGEWAY IN THE SPACE BETWEEN THEM FOR SAID AIR WHEN FLOWING BETWEEN SAID ENTERING MEANS AND SAID LEAVING MEANS, WHEREBY SAID FIRE POT HAS A MINIMUM TENDENCY TO BUCKLE AND BOOM UNDER A TEMPERATURE CHANGE, AIR FLOWS THROUGH SAID TRANSITION ZONE WITH A MINIMUM OF TURBULENCE, AND SAID RECTANGULAR CASING FITS IN A SQUARE CORNER OF A ROOM. 